sound is working but screen is blank

Hi,

My philips smart tv 43pus6504/12 has sound but the picture has disappeared.

I can see the whole screen is on, just no picture (like a back light)

I’ve tried the basic stuff like power down for different time periods but as I can’t access any menus so I can’t do anything.

the menus are working behind the darkness however, as I know if I choose the tv option the sound comes on!

I got it through a work incentive scheme but pretty sure it’s about a year old if that

thanks in advance